Automatic furnace control



L. GA'RRISON. AUTOMATIC FURNACE CONTROL.

APPLICATION FILED NOV. 1, 1919- ]Patmmted Mar. 29, 19210 Fig.1-

d Inventor.-

wydgm M 3 1 1/ f 2- W Y 2 6 w 3 no I UNHTJED STATES LLOYD GARRISON, OF SALT LAKE CITY, UT.

AUTOMATIC FURNACE CONTROL.

Specification of Letters Patent. Patented Maui. 253), 1921,,

Application filed November 1, 1919. Serial m5. 335,147.

To all whom it may concern:

Be it known that I, LLOYD GARRIsoN, a.

citizen of the United States, residing at Salt Lake City, in the county of SaltgLake and State of Utah, have invented a new and useful Improvement in Automatic Furnace Controls, of which the following is a specifi= cation.

The object of my invention is to provide a direct acting, automatic, electrically oper ated control for furnaces which operates in conjunction with a thermostat and maintains a predetermined temperature of air by opening and closing the furnace drafts, and if desired controls the feeding of fuel to the furnace.

In the accompanying drawings, reference numerals designate the same parts in all cases.

Figure 1 is a plan of the apparatus.

Fig. 2 is a right elevation.

Figs. 3 and 4 are details of the ratchet pulley.

Figs. 5 and 6 are details of the safety dev1ce.

Fig. 7 is a detail of the contact disk.

Figs. 8 and 9 are details of the switch drum that controls the mechanical feed.

The apparatus is shown in the drawings in such position that the damper of the furnace is open and the check draft closed.

Under these conditions the furnace is active and the temperature at the thermostat, 1, is

increasing. For the purposes of illustration, the thermostat is shown as the ordinary b1- metallic type, the leaf of which'bends one way when the temperature is increasing and the other way when the temperature is decreasing. As the temperature increases the leaf 2 bends toward contact 3. When 2 touches 3 the low voltage circuit energized by the bell transformer 4 is completed from the terminal 5 of the transformer, through conductor 6, leaf 2, terminal 3, conductor 7, contact spring 8, the metal of contact disk 9, shaft 10, to the base 11. From this it passes through spring 12, arm 13, sprmg 14, conductor 15, coil 16, conductor 17, back to transformer 4 at terminal 18. The current supplied to the circuit just outlined by the bell transformer energizes the electromagnet 16 which attracts armature 19 placed on one end of the lever 20. Armature 19 moves up, pulling down and closing the spring leaf switch 21. The high voltage, or motive circuit, is completed by the closing of switch 21. Current then flows from supply main 22 through terminal 23, conductor 24, switch terminal 25, switch 21, swltch terminal 26, conductor 27, coil 28, conductor 29, terminal 30, fuse 31, terminal 32, conductor 33, terminal 34, and back to the source of supply by main 35. The passage of current through the motive circuit actuates the electromagnet 28 which pulls down plunger 36. Plunger 36 is connected to sprmg 37 by cable 38 which runs over ratchet pulley 39 and is secured thereto to prevent slipping by the screw 40. The construction of ratchet pulley 39 is shown more in detail by Figs. 3 and 4. This pulley is rotated freely by the'action of spring 37 but if rotated by the action of plunger 36, shoulder 41 on the pulley engages sliding pin 42 and the crank arm 43 is rotated with the pulley. The travel of the plunger 36 is so limited by the stop 44 and the metal p1ece 45 that the pulley and crank rotate only one half revolution, or Slightly in excess thereof; when actuated by plunger 36. This closes the damper 46 and opens the check draft 47 which are connected by cables 48 and .49, respectively, to sleeve 50. Sleeve 50 rotates freely on stud 51, set in crank 43. The shaft runs in suitable bearings 53 and to it are rigidly secured the crank 43, contact disk 9, and drum 54. When crank 43 is rotated by the motion of plunger 36 acting on pulley 39, disk 9 ,and drum 54 are both rotated one half revolution. By the rotation of disk 9 one half revolution the insulation 55, shown more fully in Fig. 7 which is a left elevation of disk 9, is brought into contact with spring 8, thus breaking the low voltage circuit; also spring 70 is brought intocontact with the metal of disk 9 preparatory to the next operation. At the same time, sprin 8 drops behind the shoulder in the insu ation, thus preventing a backward motion of the disk with a consegkuent remaking of the low voltage circuit.

too .great forward rotation of the crank is prevented by leading away the chains to the damper and check draft'in proper directions. When the low voltage circuit is broken by contact of spring 8 with insulation 55, armature 19 is released and lever 20 forced back to its original position, partly by the weight of the armature and partly 39 and pin 42 is similar to that of a ratchet.

The function of spring 12, arm 13, and spring 14, Figs, 5 and 6, is that of 'a safety device. 'Without this, if for any reason pm 42 should fail to engage shoulder 41 and rotate the crank 43, the low voltage circuit would not be broken and the plunger 36 would be permanently attracted. To prevent this, the pin 58 is provided, which at the end of the half revolution of pulley 39 caused by the action of the plunger, irrespective of the breaking of the low voltage circuit at contact disk 9, strikes arm 13 and breaks its contact with spring 12. This breaks the low voltage circuit with the consequent release of plunger 36. At the termination of the reverse half revolution of the pulley 39 the pin 59 strikes arm 13 and remakes the connection. If the circuit is not then broken at disk 9 the low voltage cur rent again immediately actuates magnet 16, closes switch 21 and pulley 39 is again rotated. This is repeated until pin 42 engages shoulder 41 and th shaft is rotated, breaking the contact at disk 9. The travel of arm 13 is restricted by stop 60. In the event the damper or check draft become caught and the rotation of shaft 10 is prevented, the coil 28 is protected by fuse 31.

If it isdesircd, the apparatus may be made to control the operation of a mechanical fuel food to the furnace as well as performing the functions heretofore described. In the drawings, a control of this sort is shown as an electric switch which alternately connects and disconnects a motor driving the mechanical fuel feed. This motor circuit leaves supply main 22 and traverses conductor 61, motor 62, conductor 63, contact spring 64, segment 65, contact spring 66, conductor 67, terminal 32, conductor 33,

terminal'34, back to the source of supply by mam 35. Figs. 8 and 9 show the construction of drum 54. Thisdrum is composed of insulating material which carries the metal segment 65 and is attached rigidly to shaft 10. The action heretofore described whereby crank 43 is rotated one half revolutlon, thus closing damper 46 and opening check draft 47, also rotates drum 54 one half "revolution and breaks contact of the segment 65 with 64 and 66. This stops motor 62 which does not again operate until the next half revolution remakes the circuit. If a water motor, loose pulley, or other 359 chanical motive power is substituted for motor 62, drum 54 is replaced by a suitable mechanical device for controlling such motive power.

Under the conditions following the action above described, the furnace becomes inactive and the tem erature at the thermostat is decreasing. en it has fallen to the lower limit for which the thermostat is set leaf 2 touches contact 68. The low voltage circuit is then once more completed and current flowsfrom terminal 5 of transformer 4 through conductor 6, leaf 2, contact 68,

conductor 69, contact spring 70, disk 9, shaft 1 10, and thence follows the path previously described through coil 16'and back to transformer 4 at terminal 18. The energizing of coil 16 again attracts armature 1 9, closes switch 21, and magnet 28 is energized. The consequent attraction of plunger 36 rotates pulley 39, crank 43, and shaft 10 one half revolution in the manner heretofore described, thus openingdamper 46 and closing check draft 47. Also, disk 9 is rotated one half revolution which brings spring 8 in contact with the metal of the disk preparatory to the next operation, breaks the existing low voltage circuit by causing the spring 70 to come in contact with and drop behind theshoulder in insulation 55, releases armature 19, breaks the motive circuit at switch '21,

electro-magnet 28. 75, 76, 7 78, and 79 are.

insulating supports for the various contact springs and terminals of the electrical circuits. 80 and 81 are conductors from terminals 23 and 34 supplying the primary of.

the bell transformer 4.

The apparatus is described as usin alternating current such as is usually 0% ained from lightin circuits but it will operate the bell transformer and either alternating or direct current is used inthe motive cir cuit. If direct current is used in magnet 16, switch 21 may be attached to armature 19 without the intervention of lever 20 asthe function of the latter is to eliminate the chattering due to alternating current. What I claim as my invention is:

an electromagnet in circuit therewith, a suit? abl mounted shaft, a crank attached to one en thereof, a ratchet pulleyadj acent to the praplg'an electric switch mounted? 01} the equally as we 1 if a battery is substituted for 1. The combination, with a thermostat, of-

shaft with suitable connections thereto, a notched contact disk mounted on the shaft with contact springs bearing thereon for changing the connections of the electromagnet within the thermostat circuit and preventing the backward rotation of the shaft, an electric switch operated by the armature of the electromagnet, a second electromagnet controlled by said switch and a circuit breaker in circuit therewith, a plunger running in said second electromagnet, stops to restrict the travel of said plunger, a tension spring, a cable connecting the plunger and tension spring and running over the ratchet pulley, a pin or screw fastening the cable to the ratchet pulley, a safety device operated by the ratchet pulley for breaking and making the thermostat circuit, substantially as described.

2. The combination of a thermostat adapted to close difierent electricalcircuits at predetermined upper and lower limits of 4 temperature; an electromagnet in circuit with said thermostat; an electric switch opa plunger running in the second electromagnet; stops to restrict the travel of the plunger; a tension spring operating against the pull of the plunger; a cable connecting mostat circuit at, or near, the termination of each half revolution of the shaft, and also, by engaging the notch in the disk, prevent the backward rotation of the shaft; a safety device operated by the ratchet pulley for breaking the thermostat circuit at the terminationof the forward half revolution of the pulley and remaking it at the termination of the reverse half revolution; a switching mechanism mounted on the shaft for controlling the operation of a mechanical fuel feed; all substantially as described.

In witness whereof I have set my hand in the presence of witnesses.

LLOYD GARRISON. Witnesses:

BETH KIMBALL, E. LE ROY BOURNE. 

